• Authors:
    • Mourik, J. M. van
    • Arocena, J. M.
    • Cano, A. F.
  • Source: CANADIAN JOURNAL OF SOIL SCIENCE
  • Volume: 92
  • Issue: 1
  • Year: 2012
  • Summary: Accelerated conversion of degraded landscapes in mining areas to productive ecosystems requires stimulation of soil formation. The evolution in microstructure and changes to chemical properties in metal mine wastes 5 yr after amendments with pig manure, sewage sludge and marble waste is reported. Mine wastes had <1% organic carbon, <0.05% total nitrogen, pH ~2.0, electrical conductivity up to 20 dS m -1 and high concentrations of metals such as 22000 mg zinc kg -1 and 7000 mg lead kg -1. After 5 yr, one time amendment increased total carbon (g kg -1) from 1.4 (control) to 5.6 (marble waste +sewage sludge) to 8.3 (marble waste+pig manure). Soil pH in amended plots was 6.0 compared with 2.8 in controls. Micromorphological characteristics clearly showed that primary and secondary calcite serve as active sorption sites for organic matter. These calcitic zones were areas conducive to root growth. Soil microstructure in amended mine wastes was dominantly granular, resulting from activities of soil organisms such as fungi and enchytraeds. Results suggest organic matter can be effectively enriched in mine waste deposits through simultaneous additions of pig manure, sewage sludge and calcite. Soil amendments promoting formation of granular structure can accelerate establishment of productive landscapes in degraded mine sites.
  • Authors:
    • Gonzalez, B.
    • Rodriguez, E.
    • Campos, M.
  • Source: Bulletin of Insectology
  • Volume: 65
  • Issue: 1
  • Year: 2012
  • Summary: The use of cover crops is the most effective method to combat soil degradation due to erosion in olive cropping in Spain. Within the framework of Integrated Pest Management (IPM), a compelling question is how cover crops would affect elements of the olive-agroecosystem such as natural enemies. Accordingly, the objective of this study was to examine the effects of cereal cover cropping on natural enemy communities in olive groves. Samples of the anthropod communities were collected in olive groves under tillage and cover cropping systems at five different locations in the same province. Cereal cover crops significantly increased the abundance of parasitoids in the olive canopy, especially Ageniaspis fuscicollis Dalman (Hymenoptera Encyrtidae) a parasitoid of the olive moth Prays oleae Bernard (Lepidoptera Yponomeutidae), the most common insect pest of olive trees. However, parasitoid abundance and structure depended on olive grove location suggesting the importance of crop surroundings in parasitoid community dynamics. Predators numbers were slightly higher in tilled olive groves but no significant differences were found between the two soil management systems.
  • Authors:
    • Isla, R.
    • Urrego, Y. F.
    • Salmeron, M.
    • Cavero, J.
  • Source: Agricultural Water Management
  • Volume: 113
  • Issue: October
  • Year: 2012
  • Summary: Typical field conditions under sprinkler irrigation include low irrigation uniformity and non-uniform plant density, which can affect the crop yield and the environmental impact of irrigation. The effect of the uniformity of sprinkler irrigation and plant density on the variability of maize grain yield under semi-arid conditions was evaluated, and the relevance of the spatial variability of these two variables on the simulation of maize grain yield was tested with the DSSAT-CERES-Maize model (V 4.5). Experimental field data from three maize growing seasons (2006, 2009 and 2010) with nighttime or daytime sprinkler irrigation were used to test the model performance. Yield, irrigation depths and plant density distribution were measured in 18 m * 18 m plots divided in 25 sub-plots. Regression analysis showed that the variability of plant density and seasonal irrigation depth (due to irrigation non-uniformity) was able to explain from 28 to 77% of the variability in maize grain yield for the experiments with a relatively high coefficient of uniformity (CU) (73-84%) and high plant density (more than 74,844 plants ha -1). Taking into account irrigation depth distribution improved maize yield simulations compared to simulations with the average irrigation water applied. The root mean square error ( RMSE) decreased from 637 to 328 kg ha -1. Maize yield was over-predicted by 3% when irrigation depth distribution was not considered. Including plant density distribution in the simulations did not improve maize yield simulations. The simulated decrease in maize yield with decreasing CU of irrigation from 100 to 70% varied from year to year and caused reductions in yield ranging from 0.75 to 2.5 Mg ha -1. The ability of the model to simulate CU effects on maize yield is shown.
  • Authors:
    • Munoz-Carpena, R.
    • Gabriel, J. L.
    • Quemada, M.
  • Source: Agriculture Ecosystems and Environment
  • Volume: 155
  • Year: 2012
  • Summary: Using cover crops (CC) in semiarid irrigated areas is often limited by low nutrient and water-use efficiency. This work was conducted over 3.5 years to determine the effect on NO 3- leaching, water balance and soil mineral N accumulation of replacing fallow with CC in irrigated systems. Treatments studied during the maize ( Zea mays L.) intercrop period were: barley ( Hordeum vulgare L.), vetch ( Vicia villosa L.) and fallow. Soil water content was monitored daily to a depth of 1.3 m and used with the numerical model WAVE to describe the water balance. Determination of crop canopy parameters was based on digital image analysis, and root depth in capacitance sensor readings. Nitrate leaching was calculated multiplying drainage by the soil solution nitrate concentration. Soil mineral N was determined before sowing CC and maize. Over the study, cumulative nitrate leaching in the fallow, vetch, and barley was 346, 245, and 129 kg N-NO 3- ha -1, respectively; occurring more than 77% during the intercrop period. In dry winters, NO 3- accumulated in the topsoil, and CC controlled the NO 3- leaching during the initial maize growth stages. Vetch was less efficient than barley at controlling leaching, but enhanced soil N retention. The CC controlled NO 3- leaching and recycled N inside the cropping system.
  • Authors:
    • Infante Amate, J.
    • Bernard, C.
    • Vanwalleghem, T.
    • Toloza, A.
    • Chhem-Kieth, S.
    • Mabit, L.
    • Gonzalez de Molina, M.
    • Gomez, J. A.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 159
  • Year: 2012
  • Summary: Soil degradation is a major agrienvironmental issue under Mediterranean climatic conditions. To assess soil erosion magnitude under orchard plantation, soils in an undisturbed area - located within an archaeological protected site in southern Spain - were analysed to establish its physicochemical status, the initial 137Cs fallout and the natural level of radioactivity taking into account the content of naturally occurring radionuclides (NOR). The vertical profiles of NOR mass activities confirmed its non-disturbance. 90% of the 137Cs content was concentrated in the top 20 cm and the physicochemical parameters confirmed as well the undisturbed status of the site. The base-line level of 137Cs was established at 1925250 Bq m -2 with a coefficient of variation of 23% and an allowable error of 11%. This 137Cs background was used to assess soil erosion magnitude in a close orchard field using the 137Cs method. The maximum erosion rates reached 19 t -1 ha -1 yr -1 and a sediment delivery ratio of 29% was evaluated, both values confirming an unsustainable soil loss magnitude due to the combination of water and tillage erosion processes since the 1950s. The radium equivalent activity and the absorbed dose rate results highlighted a difference between eroded and deposition sectors in the cultivated field confirming that these parameters could be used to some extend to assess pedologic processes.
  • Authors:
    • Termansen, M.
    • Boix-Fayos, C.
    • Vente, J. de
    • Nainggolan, D.
    • Hubacek, K.
    • Reed, M. S.
  • Source: Agriculture Ecosystems and Environment
  • Volume: 159
  • Year: 2012
  • Summary: An understanding of land use change and its drivers in semi-arid Mediterranean agro-ecosystems is important for informing ways to facilitate adaptation to future environmental and socioeconomic pressures. In this paper, we mapped and quantified land use changes in the semi-arid Mediterranean agro-ecosystem of Torrealvilla catchment between 1956 and 2008. Subsequently, we detected signs of landscape fragmentation and examined the relationship between land use change trajectories and a set of biophysical factors using Generalized Additive Models (GAMs). Finally, we qualitatively evaluated the role of socioeconomic drivers on the land use change trajectories. The study provides accounts of multidirectional land use trajectories in semi-arid Mediterranean landscapes. Our analysis shows that more than 72% of the study area has undergone significant changes over the past five decades with pronounced effects on landscape composition and structure. Both biophysical and socioeconomic factors are strongly related to the observed spatial and temporal changes in land use. Three major trajectories were observed. Firstly, rain-fed agriculture is becoming less dominant; future abandonment of rain-fed agriculture should be anticipated. Secondly, expansion of forested areas is evident in higher altitudes. The trend is still likely to continue given the possibility of further abandonment of rain-fed farming and existing subsidies for reforestation of arable land. Thirdly, intensification has been observed which has occurred mainly in lower parts of the landscape on flat to gentle slopes and near main roads. Further intensification is likely to be subject to market drivers, irrigation water availability, and future rural development and agricultural policy. Overall, the study shows that even within a given locality, contrasting land use trajectories can emerge as a result of local responses to multiple drivers of change and these need to be carefully taken into account in future policy development.
  • Authors:
    • Schuhmacher, M.
    • Nadal, M.
    • Marti, E.
    • Sierra, J.
    • Roig, N.
    • Domingo, J. L.
  • Source: Agriculture Ecosystems and Environment
  • Volume: 158
  • Year: 2012
  • Summary: Wastewater treatment processes generate highly biodegradable solid wastes. As their fate is an environmental issue of great concern, public administrations promote a sustainable management of urban wastes. The objective of the present study was to analyze the systematic and periodical use, for 16 years, of anaerobically digested sewage sludge as an agricultural fertilizer by assessing the effects on some soil physical-chemical, functional, and ecotoxicological properties. The results showed that the input of sludge enhances soil properties proportionally to the application doses and/or frequency. The organic amendments increased the organic matter content (and its aromaticity), the soil nitrogen, and the microbial activity, improving carbon and nitrogen mineralization processes and some enzymatic functions. However, a maximum dose was identified (40 Mg ha -1 year -1), beyond which soil properties do not improve, and may even worsen. Regarding environmental risks, although the bioluminescent bacteria test showed no toxicity on soil extracts, potential adverse effects such as some potentially toxic elements accumulation, phytotoxicity and the likelihood of groundwater pollution by nitrates or dissolved organic matter should be taken into account. The complementarity of studying soil functioning parameters and ecotoxicological effects, together with the analysis of pollutant content, must be enhanced. This assures a more realistic assessment of long-term effects of sewage sludge-amended soils.
  • Authors:
    • Garcia-Torres, L.
    • Sanchez-Martin, L.
    • Sanz-Cobena, A.
    • Vallejo, A.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 149
  • Year: 2012
  • Summary: Urea has become the predominant source of synthetic nitrogen (N) fertilizer used throughout the world. Among the various available mitigation tools, urease inhibitors like NBPT have the most potential to improve efficiency of urea by reducing N losses, mainly via ammonia volatilization. However, there is a lack of information on the effect of N-(n-butyl) thiophosphoric triamide (NBPT) on other N losses such as gaseous emissions of N 2O and NO and NO 3- leaching. A two-year field experiment using irrigated maize ( Zea mays) crop was carried out under Mediterranean conditions to evaluate the effectiveness of urea coated with NBPT (0.4%, w/w) alone and with both NBPT and nitrification inhibitor dicyandiamide (DCD) (0.4 and 3%, w/w, respectively) to mitigate N 2O-N, NO-N and NO 3--N losses. The different treatments of U, U+NBPT and U+NBPT+DCD were applied to the maize crop in 2009 and then in 2010. The 2010 maize crop followed a fallow period, during which the 2009 crop residues were incorporated into the soil. Two different irrigation regimes were followed each year. In 2009, irrigation was controlled for the first 2 weeks following urea fertilization; whereas, the 2010 crop period was characterized by increased irrigation in the same period. After each treatment application, measurements of the changes in soil mineral N, gaseous emissions of N 2O and NO, nitrate leaching and biomass production were made. N 2O emissions were effectively abated by NBPT and NBPT+DCD and were reduced by 54 and 24%, respectively, in 2009. A reduction in nitrification rate by the inhibitors was also observed during 2009. In 2010 cropping period, NBPT reduced N 2O emissions by 4%; while the combination of NBPT and DCD treatment reduced N 2O emission by 43%. Yield-scaled N 2O emissions were reduced by 50 and 18% by NBPT and the mixture of NBPT+DCD, respectively, in 2009. Applying inhibitors did not have any significant effect on yield-scaled N 2O emissions in the 2010 crop period. Total NO losses from urea were 2.25 kg NO-N ha -1 in the 2009 crop period and 5 times lower in the following year; this may provide an indicator of the prevalence of nitrification as the main process in the production of N 2O in the 2009 maize crop. Most of the NO 3- was lost within the fallow period (i.e. 92, 81 and 75% of the total NO 3- leached for U, U+NBPT and U+NBPT+DCD, respectively), so the incorporation of crop residues was not as effective as expected at reducing these N losses. Our study suggests that the effectiveness of NBPT and combination of NBPT+DCD in reducing N losses from applied urea is influenced by management practices, such as irrigation, and climatic conditions.
  • Authors:
    • Zegada-Lizarazu, W.
    • Walter, K.
    • Valentine, J.
    • Djomo, S. Njakou
    • Monti, A.
    • Mander, U.
    • Lanigan, G. J.
    • Jones, M. B.
    • Hyvonen, N.
    • Freibauer, A.
    • Flessa, H.
    • Drewer, J.
    • Carter, M. S.
    • Skiba, U.
    • Hastings, A.
    • Osborne, B.
    • Don, A.
    • Zenone, T.
  • Source: GCB Bioenergy
  • Volume: 4
  • Issue: 4
  • Year: 2012
  • Summary: Bioenergy from crops is expected to make a considerable contribution to climate change mitigation. However, bioenergy is not necessarily carbon neutral because emissions of CO2, N2O and CH4 during crop production may reduce or completely counterbalance CO2 savings of the substituted fossil fuels. These greenhouse gases (GHGs) need to be included into the carbon footprint calculation of different bioenergy crops under a range of soil conditions and management practices. This review compiles existing knowledge on agronomic and environmental constraints and GHG balances of the major European bioenergy crops, although it focuses on dedicated perennial crops such as Miscanthus and short rotation coppice species. Such second-generation crops account for only 3% of the current European bioenergy production, but field data suggest they emit 40% to >99% less N2O than conventional annual crops. This is a result of lower fertilizer requirements as well as a higher N-use efficiency, due to effective N-recycling. Perennial energy crops have the potential to sequester additional carbon in soil biomass if established on former cropland (0.44 Mg soil C ha(-1) yr(-1) for poplar and willow and 0.66 Mg soil C ha(-1) yr(-1) for Miscanthus). However, there was no positive or even negative effects on the C balance if energy crops are established on former grassland. Increased bioenergy production may also result in direct and indirect land-use changes with potential high C losses when native vegetation is converted to annual crops. Although dedicated perennial energy crops have a high potential to improve the GHG balance of bioenergy production, several agronomic and economic constraints still have to be overcome.
  • Authors:
    • Leon-Cofreces, C.
    • Garcia, M.
    • Calvo, R.
    • Miralles de Imperial, R.
    • Martin, J.
    • Delgado, M.
  • Source: Soil Research
  • Volume: 50
  • Issue: 3
  • Year: 2012
  • Summary: Soil has an important role in the greenhouse effect as a net source or net sink of greenhouse gases. This study compared CO2 emission from broiler poultry manure (PMB) and hen poultry manure (PMH) in two different soils. A laboratory experiment was conducted to evaluate the decomposition of poultry manure by analysing carbon mineralisation. Jars were filled with soil, sealed, and placed in an incubator for 60 days, with periodic CO2 analysis. Higher emissions were found in soil amended with PMH; cumulative carbon released as CO2 was 800 mg C/kg in soil amended with PMH, and 600 mg C/kg with PMB. Data for cumulative CO2-C released from unamended and amended soils were fitted to four different kinetic models. With poultry manure, there were significant differences in the model parameters that represent the amount of total potentially mineralisable carbon and the mineralisation rate constant. After 60 days, the percentages of organic carbon mineralised for PMH were 40% and 26% for each soil, whereas the percentages were 20% and 12% for PMB.